Internal combustion engines typically have an intake system that is adapted to supply air, or a mixture of air and exhaust gas, into a plurality of cylinders. Addition of fuel in the cylinders and subsequent combustion of a mixture of air and fuel in the cylinder yields power while the engine operates. Exhaust gas produced after the combustion in each cylinder is exhausted from the engine through an exhaust system.
Typical engines recirculate a portion of exhaust gas from the exhaust system, through a valve, into the intake system of the engine. The recirculated exhaust gas is used to displace oxygen from the air entering the cylinders, and lead to engine operation the generates lower emissions. This method of lowering engine emissions is commonly referred to as exhaust gas recirculation (EGR) and is quite commonly used.
A typical EGR system for an engine requires a pressure differential to function. This pressure differential should be present between the exhaust and intake systems of an engine, whereby a pressure in the exhaust system should be higher than a pressure in the intake system such that exhaust gas is compelled to flow from the exhaust system into the intake system. This configuration, even though effective for compelling flow of EGR gas, is ineffective in producing desired engine operating parameters, such as low fuel consumption, low pumping losses, increased heat rejection to the engine's cooling system, and so forth.
These issues have been addressed in the past by, for example, use of pumps that pump EGR gas from an exhaust system pressure up to and above an intake system pressure. Such pumps have typically been secondary devices added to the engine that operate under a variety of configurations, including mechanical, hydraulic, or electrical power. Use of such secondary devices is generally impractical, expensive, energy inefficient, and complex.